The interior, roughly 37 metres across at its longest axis, is now a tangled mass of trees and dense undergrowth so thick that nobody can say with certainty what lies beneath it. That uncertainty is part of what makes the site quietly compelling: the earthworks are measurable and largely intact, but the enclosed space they were built to protect remains, for the moment, unreadable.

The rath is bivallate, meaning it was defended by two concentric earthen banks rather than the single bank more commonly seen in Irish ringforts. Between the banks runs a fosse, a wide defensive ditch, here flat-bottomed and nearly four metres across, dropping almost two metres from the crest of the inner bank. That inner bank has an unusually broad base of six and a half metres, the result of a very gradual inward slope rather than any structural failing. More intriguingly, its outer face is revetted with random courses of block-like stone slabs, a detail that may not be original to the rath's construction but added at some later point, perhaps to shore up a bank that was beginning to spread or slump. The outer bank, by contrast, is barely traceable along the eastern half of the circuit, buried under vegetation that has made systematic survey difficult. Ringforts of this kind were typically built during the early medieval period, roughly the fifth to twelfth centuries, and served as enclosed farmsteads for a single family or small community. The double-bank arrangement at An Chaisleach would have marked out a household of some local status.

The density of the overgrowth means the site is difficult to read on the ground, and both the fosse and the outer bank can only be followed intermittently. What is visible is enough to convey the scale of the original construction, but the interior remains closed off behind its own wildness, possibly concealing features that have never been recorded.